Shockproof circuit breaker with a fuse cartridge



Oct. 7, 1969 e. A. e. MARECHAL 3,471,817

SHOCKPROOF cIRcuI'r BREAKER mm A FUSE caawamem 3 Sheets-Sheet 1 Filed July 31, 1967 SHOCKPROOF CIRCUIT BREAKER WITH A FUSE CARTRIDGE Filed July 31, 1967 Oct. 7, 1969 s. A. e; MARECHAL 5 Sheets-Sheet 2 nlllulllnrllllll I 5... jv ww SHOCKPROOF cmcurr BREAKER wmx A FUSE cmmnez Filed July 31. 1967 Oct. 7, 1969 s. A. G. MARECHAL 3 Sheets-Sheet .7

United States Patent 3,471,817 SHOCKPROOF CIRCUIT BREAKER WITH A FUSE CARTRIDGE Gilles Adrien Georges Marechal, Paris, France, assignor to S.E.P.M., Paris, France, a joint-stock company Filed July 31, 1967, Ser. No. 657,415 Claims priority, application France, Aug. 8, 1966, 72,457; Jan. 20, 1967, 92,005 Int. Cl. H01h 85/48, 85/22 US. Cl. 337-201 8 Claims ABSTRACT OF THE DISCLOSURE A circuit breaker protecting the operator against undesired contact, comprising a safety tube revolvably carried inside the cavity of a support and defining, together with the inner surface of said support, an annular chamber enclosing at least one of the conductors forming the terminals of the circuit breaker. The fuse cartridge is carried by a conventional plug which, when placed in said cavity, may be rotated together with the safety tube so as to bring the latter into an operative position in which said conductor in said annular chamber registers with an opening in the tube through which it operatively engages the corresponding cap on the fuse cartridge.

Circuit breakers with fuse cartridges are well known in the art and the most frequently used are those of the so-called vertical type, wherein the circuit breaker includes, on the one hand, a support forming a cylindrical shaft provided at its lower end with a recess and an elastic terminal jaw or contact-piece connected with one of the wires of the electric lead and adapted to engage one of the ends of the fuse cartridge, while the second wire of the lead is connected with a conductive member lying in the vicinity of the opening of said shaft and, on the other hand, a cartridge-carrying plug constituted by an insulating casing enclosing a conductive member which may be a jaw or a recessed part adapted to engage the other end of the cartridge and the conductive member in the shaft opening whenever the cartridge-carrying plug is positioned over the support, the arrangement including furthermore cooperating securing means carried by the plug and by the support respectively.

Generally, these cooperating securing means are constiuted by two threads, of which one is provided on the conductive member at the opening of the shaft and the other on the conductive member carried by the cartridgecarrying plug or else said means form part of a bayonet joint.

All these arrangements proposed hitherto show the serious drawback consisting in that the operator is not protected against a fortuitous contact. In fact, the conductive member located at the input end of the shaft is always more or less within reach of the operators fingers and consequently it is preferably connected with the terminal of the electric current subjected to a minor voltage, whereas the live wire of the lead is connected with the contact piece located at the lower end of the shaft.

However, said precaution in not sufficient since the contact carried at the lower end of the shaft remains within reach of the operators finger whenever the diameter of the shaft is larger than a predetermined value and it is even always within reach of a tool or of the actual fuse cartridge, chiefly if the latter remains wedged and is released with reference to the plug when the latter is removed.

The present invention covers a circuit breaker of the so-called vertical type wherein at least the conductive member located in the vicinity of the lower end of the shaft cannot be reached from the outside.

Such an arrangement ensures an undisputable safety. In the case where only the conductive member near the opening of the shaft is out of reach, it is suflicient to design the connections in a manner such that said member may be connected with the live wire of the lead. In the case where both conductive members are out of reach, the safety is complete, whatever the connections may be.

The present invention has for its object improvements in a circuit-breaker provided with a fuse cartridge of a vertical type, comprising a support of an electrically conductive material carrying inside a shaft two conductive members connected respectively with the two wires of the lead and of which one is located near the lower end of the shaft, while the other is located near the opening of the latter and on the other hand a cartridge-carrying plug made of electrically insulating material includes a member adapted to clamp elastically one of the caps of said fuse cartridge while the opening of the shaft and the plug are designed in a manner such that the latter cannot be fitted inside said opening otherwise than when it occupies a predetermined angular position with reference thereto, after which a rotation of the plug ensures the interengagement between the two parts, which can no longer be separated translationally.

Now, according to the invention, the housing of the fuse cartridge is constituted, at least in its upper section, by a cylindrical so-called safety tube coaxial with the opening of the shaft and the inner diameter of which is substantially equal to the diameter of the caps of said cartridge, said tube being adapted to revolve freely with reference to the support of the circuit breaker underneath an inner shoulder of the shaft, whereby there is obtained between said tube and the wall of the shaft an annular space in which is housed at least the conductive member which is nearest the shaft opening, while on the other band the safety tube is provided with lateral openings adapted to allow a contact, possibly through the agency of an intermediate part between the caps of the cartridge and the corresponding conductive member or members housed in said annular space. Furthermore, the cartridge-carrying plug and the upper section of the safety tube are provided with cooperating means ensuring their simultaneous rotation which means are designed in a manner such that they are engaged whenever the plug has been fitted and held fast in the opening of the shaft after it has been set in the above-mentioned angular inoperative position allowing the interengagement of said means, whereas the lateral openings of the safety tube are arranged so as to register with the contact-forming surfaces of the conductive members housed inside the annular space at the end of the rotation executed in unison by the cartridge-carrying plug and by the safety tube so as to enter their operative position.

In order to properly understand the invention, there are described hereinafter by way of example and in a nonlimiting sense two preferred embodiments of my invention. In the accompanying drawings illustrating said emb odiments FIGS. 1 to 6 refer to a circuit breaker the safety tube of which protects the upper conductive member only, while FIGS. 7 to 14 illustrate a circuit breaker of which the safety tube separates iand insulates both conductive members,

More specifically, FIGS. 1 and 2 are cross-sections through a plane of symmetry of the plug of the first embodiment 'of a circuit breaker, respectively before and :after said plug has been angular shifted,

FIG. 3 is a perspective view of the support of the circuit breaker,

FIGS. 4 to 6 illustrate respectively in perspective view the contact piece on the plug, the input blade and the safety tube as out along the plane of FIG. 1,

FIG. 7 a cross-section of the second embodiment of a circuit breaker illustrated in. its engaged position, the cross-section passing through its vertical plane of symmetry,

FIG. 8 is a perspective view corresponding to FIG. 7 after removal of the plug,

FIG. 9 is a perspective view of the plug cut off along its diametrical plane of symmetry,

FIG. 10 a perspective view of the clamping collar carried by the plug,

FIG. 11 is a perspective view of the cartridge held fast in the plug,

FIG. 12 is a perspective view of one of the conductive members, constituted by a contact-making jaw,

FIG. 13 is a perspective view of a contact-making jaw clamping the safety tube FIG. 14 is a diagrammatic horizontal cross-section of the safety tube surrounded partly by protecting walls and a contact-making jaw.

Turning to FIGS. 1 to 6, the circuit breaker provided with a fuse cartridge is constituted by a support 1 of insulating material forming a shaft or cavity, the lower end of which carries an elastic contact piece 2 connected with the output terminal '3 of an electric lead, said contact piece being adapted to engage one of the caps 4 of the fuse cartridge 5. On the other hand, a cartridge-carrying plug 6 carries inside a casing or cap 7 of electrically insulating material a contact piece 8 adapted to engage the opposite cap 9 of the fuse cartridge 5.

The contact piece 8 rigidwith the casing 7 appears as a slotted socket (FIG. 4) projecting beyond the casing 7 and carrying at its outer end two diametrically opposed, finger-like studs 10a and 10b so that the elasticity of the slotted socket urges said studs apart.

The support 1 includes a pedestal 11 carrying an outer cylindrical wall 12 of which the upper circular opening 13 is sufliciently large to receive the plug casing 7. Inside the support 1, a safety tube or ring 14 fitted revolvably over the pedestal 11 iorms with the outer wall 12 of the support an annular space 15 near the upper end of the support. The wall 12 is provided with an inner shoulder 16 (FIG. 2) covering the upper edge of the tube 14 and adapted furthermore to limit the sinking of the plug inside the support, since it serves as an abutment for the lower edge of the casing 7. The shoulder 16 and tube. 14 are provided each with two diametrically opposed notches illustrated respectively at 17a, 17b, and at 18a, 18b.

An input contact blade 19 connected with the live terminal 20 of the lead (see also FIG. in the shape of a half annulus 21 is housed inside the annular space 15. It includes two arms or projections 21a, 21b extending in parallelism with the of the support into the annular space 15 in a manner such that their ends are subsantially flush with the upper edge of the tube 14. The projections 21a and 21b, as well seen in FIG. 5, are outwardly concave.

The safety tube -14 carries in a plane perpendicular to that of the notches 18a and 18b two diametrically opposed shaped bosses as illustrated at 22 (FIG. 6), said bosses being adapted to cooperate with the projections 21a and 21b of the input blade for holding the tube 14 fast in a so called inoperative position.

In vertical registry with each ot the notches 17a and 17b of the shoulder '16, the wall 12 is provided with an inner boss 23a, 23b which the studs a, 10b elastically engage in the inoperative position of the tube 14.

Lastly, the elastic contact pieces 2 and 8 are held fast within clamping rings 24a and 24b, respectively, the ring 24b being of a greater length than the ring 24a so as to ensure in a conventional manner a more substantial clamping effect for the contact piece 8 than for the contact piece 2. Thus, when the plug 6 is removed, the

cartridge 5 is released by the contact piece 2, while remaining clamped inside the contact piece 8.

The operation of the arrangement is as follows:

The cartridge 5 is inserted inside the cartridge carrying plug, its upper end 9 being clamped elastically inside the contact piece '8. The circuit breaker as in the position illustrated in FIG. 1, that is, the notches 18a and 18b of the tube 14 register with the corresponding notches 17a and 17b of the shoulder "16 and the tube 14 is held fiast in said position due to the engagement between the projections 21a and 21b of the input blade 19 and the shaped bosses '22 of tube 14. The cartridge 5 is inserted into the circuit breaker through the opening 13 by holding the casing 7 and insuring, by suitably rotating the plug 6, that studs 10a and 10b pass through notches 17a, 17b. It is thus seen that said studs and notches iorm complemental means permitting introduction of the plugs into the support only when these two are at a predetermined angular position with respect to one another. Said studs extend thus downwardly through said notches so as to nest in notches 18a and 18b in the tube 14 and to bear elastically against the bosses 23a and 23b on the wall 12, when the lower cap 4 of the cartridge 5 has reached its position of engagement with the contact piece 2. This downward movement is limited by the engagement between the lower edge of the casing 7 and the shoulder 16.

The circuit breaker is now in its so-called inoperative position. The plug and consequently the cartridge may be removed by a mere tractional stress, but in the absence of such a tractional stress, these parts remain fast in position by reason of the elastic contact between the studs 10a and 10b and the bosses 23a, 23b.

Furthermore, although the lower end 4 of the fiuse cartridge is connected through the contact piece 2 with the output terminal 3, the line terminal 20 which is subjected to the input voltage is not electrically connected with the other end (cap 9) of the cartridge, so that the electric circuit remains open.

The plug is then subjected to a rotation through in either direction. At the beginning of said rotary movement, the studs 10a, 10b move oil? the bosses 23a and 23b and the bosses 22 move ofi the projections 21a and 21b. The plug 6 carries along with it during its rotation the tube 14 by virtue of interengaging complemental means formed of the bent studs 10a, 10b and the notches 18a, 18b. The plug 6, as its rotation starts, is held fast underneat'h the shoulder 16 and thus can no longer be pulled out from the support. Upon completion of this rotation through 90 (FIG. 2), the studs 10a and 10b enter into an elastic contact with the projections 21a and 21b of the conductive input blade 19. Said contacting is made easier by the arcuate shape given to said projections.

The upper end 9 of the cartridge 5 is now connected with the input blade 19 through the contact member 8, of its studs 10a and 10b and the projections 21a and 21b. The electric circuit is thus closed.

Thus, the circuit breaker is adapted to pass from its inoperative to its operative position by a mere rotation through one quarter of a revolution. It acts then as a circuit breaker, but it provides complete safety for the operator. As a matter of fact, when the plug has been brought into its inoperative position and then removed out of its support, the sole parts with which a fortuitous conact may be dangerous, to wit, the input blade 19 and its projections 21a and 21b are entirely enclosed inside a chamber constituted by the wall 12, tube 14 and shoulder 16 and consequently they cannot be reached from the outside. It should also be remarked that, if a cartridge is introduced alone into the support or accidentally separates from the plug when the latter is removed, the fortuitous contact between the upper end 9 of the cartridge and the users finger i by no means dangerous in e th lower end of said cartridge is connected with the output terminal of the lead.

According to another embodiment illustrated in FIGS. 7 to 14, the circuit breaker adapted to carry a fuse cartridge 101 (FIG. 11) includes a support 102 and a plug 103, both of which are made of an electrically insulated material. Inside the plug 103 is fitted a member 104 adapted to elastic-ally clamp the upper cap 101a of the fuse cartridge 101. Said member is held fast in the plug through slashes which are not entirely open, as shown at 104a and 1041) (FIG. so as to form tongues cooperating with ports such as 105 formed in the lower end of the plug (FIG. 9). Preferably, however, said member 104 is furthermore wedged in position by an insulating intermediate member 106 (FIG. 7) fitted with a force fit inside or screwed into said plug and designed in a manner such as to define together with the lower surface of the cover of the plug, a chamber 107. The member 104 is provided with two diametrically opposed projections 108a and 10% extending away from the plug cover, the spacing of said projections being slightly smaller than the diameter of the cap 101a of the cartridge so as to be capable of elastically clamping the latter. The cover of the plug is provided with a central opening 109 preferably closed by a translucent material, while an indicator light which is not illustrated is housed inside the above-mentioned chamber 107 and is connected in a conventional manner so as to remain ignited when the circuit is closed.

When the fuse cartridge is engaged by the projections 108a and 1081), it becomes affixed to the plug 103. This assembly illustrated in FIG. 11, is capable of being inserted in or removed out of the support 102 as a unit, as disclosed herein-after.

The lower end of the lateral outer surface of the plug carries two studs 110a and 11012 in diamertically opposed relationship, said two studs having different :heights and thicknesses and being located substantially in vertical registry with the extensions 108a and 108k of the clamping member 104.

The support 102 includes a shaft or cavity 111 communicating with the outside in a conventional manner (FIG. 8) on the one hand through an upper opening 112 and, on the other hand, through two tubular ports 113a and 113b extending normal to shaft 111 and adapted to receive the binding posts for the two wires of the lead. To this end, channels 114a and 114k allow a screwdriver to reach ports 113a and 113b in registry with the locations of the corresponding screws 115a and 115b of the binding posts for the two wires of the lead (FIGS. 7 and 8). The upper opening 112 is defined by a radial inner flange 116 the diameter of which is sufficient to receive the plug 103. Flange 116 is provided with two notches such as 117a formed in diametrically opposed relationship in a vertical plane perpendicular to the vertical plane of symmetry of the support, while the breadths of said notches correspond with those of the studs 110a and 110b in a manner such that the plug 103 cannot enter the opening 112 except in a predetermined relative angular position between the two parts.

Inside the shaft 111 are formed two arcuate protecting walls 118 and 119 extending each to both sides of the vertical plane of symmetry of the ports 113a and 113b and the inner surfaces of which (form portions of a cylinder coaxial with opening 112.

A vertical cylindrical tube 120 the inner diameted of which is suificiently large to permit passage of the caps 101a and 10112 of the cartridge is positioned between the two walls 118 and 119 and rests within a shoulder 121 at the bottom of the shaft 111 inside which it may revolve freely, its stability being ensured by a shoulder 122 formed on its upper section cooperating with the upper section of the inner surface of the shaft 111, while the upper edge of the tube 120 engages the underside of the flange 116 surrounding the opening 112 of the support. The tube 120 is provided at its upper end with two diametrically opposed notches 123a and 123b starting from the upper edge of the tube and the breadth and depth of which correspond respectively with the thickness and height of the corresponding studs a and 11012 carried by the plug 103. In a diametrical plane perpendicular to that of the axes of the notches 123a and 123b, the tube is provided with four windows of which two upper windows 124a and 1241b are located underneath the shoulder 122 lying at the level of the upper cap 101a of the fuse cartridge, while two lower windows 125a and 1251) are located at the level of the lower cap 101b of said cartridge.

Two contact-making jaws 126a and 12Gb of which one is illustrated in detail in FIG. 12, are each constituted by a U-shaped conductor 128 the arms of which 1280 and 128b are spaced to an extent equal to the outer diameter of the tube 120, while their ends are bent inwardly of the U at 129a and 129!) and a vertical extension 1280 of the member 128 in a plane perpendicular to said arms is rigid with a binding post 127a (FIGS. 13 and 14).

The upper jaw 126a is inserted inside the support 102 while its binding post 127a is located inside the port 113a and its connection with the extension 128c is located between the protecting wall 118 and the inner surface of the shaft 111. The extension 1280 is directed upwardly so that the arms 128a and 12% lying to either side of said wall 118 may clamp the tube 120 between their bent ends 129a and 1291) in a diametrical plane perpendicular to the vertical plane of symmetry of the support and at the level of the windows 124a and 1241).

Similarly, the jaw 126b is located inside the support 102 and its binding post 1271: is carried inside the recess 113b, while its extension 1280 is directed downwardly so that the arms of said jaw surrounding the protecting wall 119 may clamp the tube 120 in a diametrical plane perpendicular to the vertical plane of symmetry of the support and at the level of the windows 125a and 12517. In order to reinforce the elastic clamping obtained, each of the contact-making jaws is held peripherally by a U-shaped spring such as 130 the ends of the arms of which are bent inwardly and engage the concave surfaces of the bent ends 129a and 12% (FIGS. 13 and 14).

In the diametrical plane passing through the notches 123a and 123b formed in the wall 120 and on the outer lateral surface of the latter, there are provided at the level at least of the upper or lower windows, longitudinal grooves 131a, 131b. Similarly, two further diametrically opposed grooves 132a, 1321) formed on said outer surface at the same level are located respectively between one of the grooves 131a, 1311; and the corresponding windows 124a, 1241:.

Lastly, at the upper end of the inner surface of the tube 120, two recesses 133a and 1331) starting from the inner shoulder 122 and registering vertically with the notches 123a and 123b are adapted to receive the ends of the extensions 108a, 1081) of the clamping member 104 in the plug 103 (FIG. 14).

The operation of this embodiment is as follows:

The cartridge 101 is fitted inside the plug 103 by clamping fast the cap 101a between the extensions 108a and 108b of the member 104 rigid with said plug. The plug provided with its cartridge is then inserted inside the tube 120 through the opening 112. When in place, the cartridge is surrounded along its entire length by tube 120. Said insertion can be performed only if the following two conditions are satisfied:

Each notch such as 117a in the opening 112 should register with the corresponding notch 123a, 123b of the tube 120, while the plug should be inserted in a single predetermined angular position for which each of the studs 110a, 1101] of said plug registers with the notches 117a and 123a, b corresponding thereto. Said double condition being fulfilled, the cartridge may be urged down to the bottom of the tube 120, the lower end of said plug engaging the inner edge of the shoulder 122 of the tube 120, while the extensions 108a, 108b on the member 104 engage recesses 133a, 133!) formed in the inner surface of the tube 120. In this position the gates in the tube 120 are located in the plane of symmetry of the support, as illustrated in FIG. 13. The jaws 126a and 1261; clamp the tube 120 in a vertical plane perpendicular to said plane of symmetry and the bent ends 129a, 12% on said jaws engage the bottom of the grooves 131a, 13112 and prevent thus any rotation of the tube 120 in the absence of an outward force.

There is then imparted to the plug a rotary movement, and studs 110a and 110b, nesting in the notches 123a, 12% and sliding along the lower surface of the flange 116 within the opening 112, carry along with them the tube 120 in their rotary movement. At the same time, the bent ends 129a, 12912 of the contact-making jaws leave the grooves 131a, 131b and engage the grooves 132a, 13212. If the application of force causing rotation of the plug is discontinued, the arrangement remains steady in its so-called circuit-breaking position in which the circuit is not closed and further, the plug cannot be separated from its support because the studs 110a, 110b engage the underside of the flange 116.

When the rotary movement is continued, the bent ends 129a, 1291) of the jaws leave the grooves 132a, 132b and engage the windows 124a, 124b in the tube 120 (FIGS. 7, 8 and 14). Thus, the upper jaw 126a engages the cartridge cap 10111 through the windows 124a, 124b, while the lower jaw 126b engages the cap 10112 through the windows 125a, 125b. The circuit is now closed between the binding posts 127a, 12712 and consequently between the two wires of the lead which are clamped by said posts respectively.

The plug 103 cannot be removed out of the support 102 unless a reverse rotation brings the notches 123a, 123b into registry with the notches such as 117a.

In this inoperative position for which the gates lie in the plane of symmetry of the support and of the jaws, the cartridge introduced into the tube 120 is no longer in contact with the upper jaw nor with the lower jaw and therefore the operator may touch its upper end without any danger. Similarly, for its inoperative position, if the cartridge is removed, no fortuitous contact can be obtained with either of the two jaws which are both completely concealed by the wall of the tube 120 and even a bent tool introduced through one of the windows 124a, 124b, 125a, 125b cannot enter into contact with said jaw from which it is separated by the insulating protecting walls 118 and 119.

It is thus seen that this embodiment provides complete protection without the necessity of designating either of the posts 127a, 12712 as an input or an output.

What I claim is:

1. A circuit breaker of the type including a replaceable fuse cartridge with *two conductive ends, one of which is receivable and engagea-ble by a manually operable plug assembly, comprising,

(A) a support means having (1) a cavity and (2) an opening through which said plug is adapted to be inserted to position said cartridge in said cavity,

(B) a first complemental means carried by said support means on the one hand and by said plug assembly on the other hand to permit insertion of said plug assembly with said cartridge into said support means only at a predetermined angular position of said plug assembly with respect to said support means and to prevent linear removal or said plug assembly from said support means when said complemental means are brought out of alignment by turning said plug assembly in said support means subsequent to said insertion,

(C) an electrically insulating tube means rotatably disposed within said cavity in coaxial relationship therewith and adapted to receive said cartridge,

(D) an annular chamber defined by the outer lateral surface of said tubular means and said support,

(E) a second complemental means carried by said plug assembly on the one hand and by said tube means on the other hand, said second complemental means assuming an interengaging relation upon said insertion to cause a rotation of said tube means in unison with said plug assembly when the latter is manually turned,

(F) at least two electrical contacts disposed within said cavity, one of said contacts being permanently connected to the input terminal of a lead and associated with one conductive end of said cartridge, another of said contacts being permanently connected to the output terminal of said lead and associated with the other conductive end of said cartridge, at least the contact connected to said input terminal being disposed in said annular chamber and being shielded by said tube means prior to said insertion and prior to said rotation in unison so as to render said contact in said annular chamber electrically inaccessible through said opening of said support means, and

(G) rotating means permitting establishment of electrical connection between the contact disposed in said annular chamber and an end of said cartridge upon completion of a rotation of said plug assembly and said tube means through a predetermined angle.

2. A circuit breaker as defined in claim 1, wherein said first complemental means is formed of at least one notch in said support adjoining said opening and of at least one finger-like conductive stud carried by said plug assembly and being in continuous electric contact with one conductive end of said cartridge; said second complemental means is formed of at least one notch provided in said tube means and of said finger-like stud of said first complemental means; said notch of said first complemental means and said notch of said second complemental means are in alignment to permit an interengagement of said second complemental means upon said insertion; said contact connected to said input terminal is held in said annular chamber in such a manner that it is engaged by said fingerdike stud upon completion of said rotation through a predetermined angle.

3. A circuit breaker as defined in claim 2, wherein said contact connected to said output terminal engages a conductive end of said cartridge upon said insertion.

4. A circuit breaker as defined in claim 2, wherein said rotating means is formed by said finger-like stud.

-5. A circuit breaker as defined in claim 1, wherein said first complemental means is formed of at least one notch in said support adjoining said opening and of at least one stud carried by said plug assembly; said second complemental means is formed of at least one notch provided in said tube means and of said stud of said first complemental means; said notch of said first complemental means and said notch of said second complemental means are in alignment to permit an interengagement of said second complemental means upon said insertion; said cartridge, when in place in said support means upon said insertion, is surrounded along its entire length by said tube means; said contact connected to said input terminal and said contact connected to said output terminal are held in said annular chamber adjacent the conductive ends of said cartridge and adapted to contact said conductive ends upon said rotation through a predetermined angle.

6. A circuit breaker as defined in claim 5, wherein said rotating means is formed of windows provided in said tube means at the height of each conductive end of said cartridge; said contacts in said annular chamber include conductors urged against said tube means at the height of said windows, said conductors are adapted to project into said windows and contact said conductive ends upon said rotation through a predetermined angle.

7. A circuit breaker as defined in claim 6, including wall means integral with said support and disposed in said cavity between said tube means and said contacts in said annular chamber in such a manner that said windows in said tube means directly face said wall means prior to said rotation in unison.

8. A circuit breaker as defined in claim 1, wherein said first complemental means is formed of at least one notch 9 in said support adjoining said opening and of at least one stud carried by said plug assembly; said second complementai means is formed of at least one notch provided in said tube means and of said stud of said first complemental means; said notch of said first complemental means and said notch of said second complemental means axe in alignment to permit an interengagement of said second complement-a1 means upon said insertion; at least one of said contacts are held in said annular chamber adjacent a. conductive end of said cartridge; said rotating means is formed of a window provided in said tube means at the height of said conductive end of said cartridge; said contact in said annular chamber includes a conductor urged against said tube means at the height of said window, said conductor is adapted to project into said window and con- 15 tact said conductive end upon said rotation through a predetermined angle.

References Cited UNITED STATES PATENTS 1/1939 Batcheller 200129 X 9/1958 Duerkob 200129 X BERNARD A. GILHEANY, Primary Examiner 0 H. B. GILSON, Assistant Examiner US. Cl. X.R. 337186 

